In stores such as a supermarket, a registration terminal operated by a customer for himself (or herself) is beginning to be in practical use. A customer causes a registration terminal to read a bar code or the like attached to a product to be purchased, and thus performs registration of the product to be purchased. Thereafter, the customer purchases the registered product by inserting money displayed on a screen into a registration terminal.
There is Patent Document 1 as an example of a document disclosing a technique relevant to such a registration terminal. Patent Document 1 discloses an invention with which it is confirmed that a product is scanned. Specifically, the invention of Patent Document 1 detects that (1) a product is extracted from a shopping basket and that (2) a product is took into a storage bag. Further, this invention gives notice of an error warning in a case where a product is not scanned between (1) and (2).